CHROMOSOME-ABNORMALITIES AND P53 EXPRESSION IN A SMALL-CELL CARCINOMAOF THE BLADDER

Chromosome studies on a highly malignant tumor, a small cell carcinoma of the bladder (the first to be studied cytogenetically), showed a hy pertriploid mainline and a hypertetraploid minor line. Extensive chrom osomal rearrangements were present in both lines, some rearranged chro mosomes being seen in only one of the lines, while others, derived fro m chromosomes 6, 9, 11, 13, and 18, were seen in both. Although differ ent giant chromosomes were present in the two lines, they shared a pos sibly significant common feature: multiple copies of 2q. DNA flow cyto metry confirmed that the tumor had a hypertriploid main mode and showe d that dysplastic surface epithelium present in the histologic materia l also had a hypertriploid DNA index. p53 expression in the tumor was demonstrated by flow cytometry.